1. Field of the Invention
The present invention relates to a transmission cooling system for a saddle-type vehicle such as an all-terrain vehicle.
2. Background of the Invention
All-terrain vehicles have outstanding performance on pavement and also demonstrate high maneuverability under severe conditions including off-road and marshy conditions. The basic structure of this type of vehicle comprises a frame fitted with four wheels, an engine mounted thereupon, and a seat as well as a fuel tank located above. When a belt, instead of a chain, is used as the mechanism for transmitting engine output to the wheels, the temperature within the belt case rises due to friction heat, and that heat reduces the belt""s durability. Thus, moving air is actively taken into the belt case to cool the belt while the vehicle is underway and it is discharged from the belt case after cooling the belt.
For example, in the cooling system of a belt-type transmission stated in the gazette of Japanese Kokai Publication Hei-10-110813, the exhaust port is connected to a space below the vehicle seat via a flexible exhaust duct and is structured so as to discharge toward the engine which is located in front. Also, in the power transmission device stated in the gazette of Japanese Kokai Publication Hei-11-11171, the exhaust duct is configured so as to enhance the transmission cooling properties. However, in these and other conventional cooling mechanisms, the exhaust duct is opened at a high point on the vehicle to avoid intaking water and other debris. Usually, the aperture of the exhaust duct is situated near the rear fender. Due to the low heat resistance of the resin material used to make the fender, this positioning of the exhaust duct may lower the endurance of the rear fender.
It is accordingly a primary object of the invention to provide a transmission cooling system that cools the belt drive without lowering the endurance of the rear fender.
This is achieved by providing a transmission cooling system that maintains high waterproof properties and demonstrates outstanding countermeasures against heat.
In accordance with the invention, there is disclosed a cooling system for a transmission in a vehicle, such as an all-terrain vehicle. In one embodiment, the cooling system has an induction duct that inducts cooling air into a belt case that houses a transmission. The system also has a discharge duct that exhausts air from the belt case. The vehicle typically has a transmission, that changes the drive-power speed of a crankshaft transmitted via a clutch at a desired speed-change ratio, installed transversely offset to one side. In such a vehicle, the aforementioned induction duct is opened at one end within a box-type induction box located generally in the transverse center of the vehicle. The induction box also has an air induction port that is opened at a position near the bottom of the front fender, while the discharge duct extends to the rear of the rear fender below the seat forming a generally xe2x80x9cUxe2x80x9d shape when viewed from the rear. The discharge duct opens so that the exhaust does not directly strike the rear fender.
Pursuant to the present invention, the transmission cooling system is characterized by the fact that the aperture of the discharge duct is directed toward the side of the rear fender and a plate is attached so as to cover the aperture. Furthermore, the induction duct is linked to the belt case between the clutch and the drive pulley. A cooling-air guide unit is installed near this belt case linkage facing a cooling fan that rotates with the drive pulley so as to circulate cooling air. The inner wall surface of the aperture of the discharge duct on the side of the belt case to the outside in the vehicular transverse direction is positioned at the back of the movable face on one side of a driven pulley when the transmission is at the maximum reduction ratio.
In an embodiment of the present invention, cooling air can be actively taken into the belt case by installing an induction duct and a discharge duct before and behind the transmission. In such a case, the aperture of the induction side and the aperture of the discharge side are separated from the wheels by situating them in the center transversely, thereby reliably preventing the penetration of water, mud, and other debris into the apertures. In particular, the penetration of water, mud, and other debris during the induction of cooling air is prevented by locating the aperture of the induction duct near the bottom of the front fender. Furthermore, interaction with the rear fender is minimized by locating the aperture of the discharge duct so that the exhaust does not directly strike the rear fender.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.